When Dorothy Jean Tillman II successfully defended her dissertation in November 2023 to earn her doctoral degree from Arizona State University, she couldn’t wait to share the news with her best friend.

“It was a surreal moment,” Ms. Tillman said, “because it was crazy I was doing it in the first place.”

Ms. Tillman, at only 17, became the youngest person to earn a doctoral degree in integrated behavioral health from Arizona State’s College of Health Solutions, all before she was…